Even in his lighter moments, Mario Balotelli trails a whiff of brimstone. On Sunday he was at his most devilish, scoring a goal that may have helped decide the destiny of the Premier League title at a time when he should have been taking an early bath and contemplating a four-match suspension.

Balotelli made his appearance in the 66th minute as a belated replacement for Edin Dzeko, whose clumsiness had been holding Manchester City back ever since he got in the way of Sergio Agüero's shot in the 18th minute. To begin with, this looked no more likely to be Balotelli's day.

His first significant contribution, in the 79th minute, was to commit a foul on Benoît Assou-Ekotto, for which he quite properly earned a yellow card. Four minutes later his optimistic attempt to shoot from a couple of yards outside the Tottenham area was blocked by Scott Parker, who fell and immediately received two blows to the head, the first from the back of the Italian's left leg – almost certainly accidental – but then, as he rolled, the studs of his opponent's right boot jabbed backwards with what looked very much like intent.

Howard Webb, that generally excellent referee, gave a free-kick but took no further action. But if the backheel was clearly visible from the press box then it should have been spotted by one of his assistants, and the result would have been a straight red card. This may have been Webb's most controversial decision since he allowed Nigel de Jong to stay on the pitch after planting his studs in Xabi Alonso's chest during the World Cup final in Johannesburg 18 months ago.

And so it was that Balotelli was still available to meet the ball inside the visitors' penalty area in the fourth and final minute of added time, and to go to ground under Ledley King's desperately untidy challenge. Webb was as justified in awarding the penalty as he had earlier been incorrect in allowing Balotelli to remain on the pitch.

Whoever writes Balotelli's scripts dictated that he would get to his feet and take the penalty, which he tucked, after a cunning little hesitation in his short approach, inside Brad Friedel's right-hand post. Afterwards he was asked if he had felt much pressure – an inevitable inquiry, but an utterly redundant one. "No, nothing," he said. "I was calm, like every time I take a penalty." No doubt he will be similarly unruffled by any action the Football Association's disciplinary committee decides to take.

An incident that would have left a less experienced manager frothing at the mouth drew nothing more than a ruefully phlegmatic response from Harry Redknapp, whose self-control in the light of severe disappointment gave additional impact to his measured words. "I don't like talking about people kicking people," the Spurs manager said. "I'm the last person to talk about getting sent people sent off, but it was blatant. He [Balotelli] reacts like that to challenges. Of course he's a good player. We all know he's a talent. It's not something I understand, why he should backheel someone in the head when he's on the floor. It's not a nice thing to do, is it? It's not my game."

Redknapp's dismay was deepened by the knowledge that his side had not only mounted a stirring recovery to square the match after falling 2-0 behind on the hour but had come within a whisker of taking all three points themselves in the first minute of added time. Jermain Defoe, whose opportunist goal had launched the comeback, came agonisingly close to steering home Gareth Bale's cross.

Besides avenging the 5-1 defeat at City's hands in north London at the end of August, a third goal for Spurs at that moment would surely have transformed the contest for the title, taking Redknapp's side to within two points of the leaders. The effect on their morale, too, would have been profound, putting them in good heart for their visits to Anfield, the Emirates Stadium and Stamford Bridge in the next couple of months.

When a throbbing sense of injustice eases, they may console themselves with more positive memories of their trip to east Manchester. In the first 10 minutes of the match Spurs passed and moved with the frictionless grace traditionally associated with the best Tottenham sides and their comeback in the last half-hour often reduced their illustrious opponents to a state of panic.

Prompted by the backheader with which Stefan Savic failed to clear Younès Kaboul's long clearance, Defoe's goal was a superb example of the master poacher at work, gambling on the merest hint of an opportunity. Aaron Lennon created Spurs' second with an intelligent square ball to Bale, whose instant shot curled irresistibly beyond Joe Hart's dive. A third goal would not have flattered them.

And all to no avail, at the end of a match in which proved, for those – unlike Redknapp – who have yet to learn the lesson, that when the gods of fair play decide to take a day off, there is nothing to be done.